The equipment employed to adjust sails and rigging on modern sailing yachts has become increasingly sophisticated. In general, pulleys or bearing blocks are used in a variety of locations to provide a mechanical advantage on various control lines or sheets.
Most sailboats have a foresail called a genoa which is generally triangular in shape and has the leading edge or luff attached to the forestay, with the leading lower corner or tack attached to the deck at the bow of the boat. The fullness and shape of the sail is adjusted by a line or sheet secured to the free corner or clew of the sail. The sheet is passed through a pulley or so-called "lead block" secured to the deck on each side of the boat, and the sheet is routed aft to a winch near the cockpit of the boat, by which the sheet may be hauled in and released. In most cases, the lead block is mounted on a track extending in a fore and aft direction, which allows the angle between the clew of the sail and the lead block to be adjusted. Also, an adjustment along the track may be made to accommodate various sizes of sails.
Particularly in the case of larger sailboats, it is now common to provide one or more pairs of side-by-side tracks on both the port and starboard side of the boat. Each of these tracks carries a genoa lead block which may be adjustably positioned along the length of the track. A separate control line or sheet is passed through each block, and one of the control lines is attached to the genoa. This arrangement allows for a greater degree of adjustment of the sail. For example, the inner track might be used for beating or sailing close to the wind, in order to provide a flatter and more efficient sail shape and profile, or optimum tacking angle. The outer track might be used when sailing off the wind, or reaching. Separate tracks may also be spaced in a fore-and-aft direction.
In the arrangement described above, at least four separate sheeting systems are required, two on each side of the boat, and each includes a separate track, block and line. In order to change from an inner to outer track and vice versa, the boat is placed on the opposite track to relieve tension on the working sheet on one side, and then the leading edge of the sheet is detached from the sail and is replaced by the other.
From the foregoing, it may be seen that the use of pairs of tracks for genoa lead cars are the cause of a great deal of clutter and confusion on the deck. Particularly with larger yachts, the lead blocks must be extremely strong and securely mounted against upward and rearward forces due to the very high loads encountered. Under sailing conditions, the extra and unused parts tend to foul lines or cause mishaps.
Another general consideration applicable to genoa lead blocks is the amount and height of the fittings or hardware projecting upwardly from the deck. It is desirable to maintain a low profile with such equipment for two reasons. First, the cut or shape of many geonas is such that the foot of the sail and the clew extends close to the deck surface, and the sheave of the block should be located close to the deck as possible. Second, racing sailboats wish to minimize windage or air friction against fittings in order to increase the maximum speed of the boat.
In the prior art, it is known to provide a pulley having a shackle or loop at the foot of the block. The shackle is retained by a pin or by a spring loaded latch to enable removal of the pulley. The detaching means available available in the prior art are not, however, suitable for genoa lead cars because they have a high profile and do not provide adequate strength without unacceptable bulk. Also, attachment of a block at a single location on a traveler car may cause the car to bind on the track.